Over the past decade a growing shortage of donated organs has greatly increased the number of patients who have developed complications of end-stage cirrhosis including hepatocellular carcinoma (HCC) and the mortality for patients awaiting liver transplantation (LT). Living donor liver transplantation (LDLT) was conceived as a way to increase the availability of donated organs and was initiated in infants and children more than a decade ago. Controlled trials demonstrated the safety and efficacy of this procedure. Recently, LDLT has been adapted for the adult. Since then patients, their families and the transplant community have embraced this procedure despite reports of donor morbidity, mortality and early reports that recipients may have increased post-operative complications and reduced survival compared to CADLT. The specific aims of the LDLT cohort study is to define the short and long term risks of morbidity and mortality for the adult donor and to determine the efficacy of this procedure for the adult recipient compared to patients undergoing LT with a cadaveric liver (CADLT). Individuals interested in becoming living donors will be asked to participate in this study. Those who are selected and undergo the surgical procedure will be followed at periodic intervals to define the long term morbidity and mortality of the procedure. Individuals not selected as living donors will be matched to the actual donors 2:1 by age, race and gender and also followed prospectively as a donor control group. Individuals being evaluated for LT will be asked if they would be interested in undergoing LDLT. Those patients who identify an acceptable donor and undergo LDLT will be followed prospectively at periodic intervals to define the short and long term morbidity and mortality associated with this procedure. Those patients who are unable to identify a living donor will be matched to an actual LDLT recipient 2:1 by age, race, gender, disease etiology and severity of liver disease (MELD score). These patients will act as the recipient control group and will and be followed prospectively before and after they undergo CADLT. Ancillary studies accompanying the main trial will specifically evaluate the ability of LDLT to improve the long term outcome of patients with HCC and to evaluate the effects of donation and LDLT on hepatic histology.